It is known that a plastic lens with high refractive index can be obtained by reacting a polyisocyanate compound with a polythiol compound (see, Patent Literature 1, for example). In Patent Literature 1, a sulfur-containing urethane-based resin lens which is obtained by heating and curing a composition containing tetrathiol and at least one ester compound selected from a polyisocyanate compound, a polyisothiocyanate compound, and an isothiocyanate compound having an isocyanate group is disclosed. It is described that the lens is colorless and transparent and has a physical property of excellent heat resistance due to high refractive index and low dispersion and also excellent productivity.